adjustable upper rear control arms

[tcrist]

Dv, thanks for the info and the picture. Can you tell me then what the upper holes are for? Maybe just an extra set of holes for alignment when they are fixturing the frame for welding?

John, maybe you could just move your trailing arms to the lower holes rather then purchasing the adjustable ones. Could save you a few hundred dollars.

Thanks guys,
Terry

PS. Is that the upper adjustable arms that are on capteddies Cobra? They look nothing like mine.

[Double Venom]

Terry,
Only about 95% sure.....way back when CR's was a Rutherford company, he used/attempted to use the Cobra frame for the Healey's. The Healey's were popular then and the body was changed and also making their own frame for the Healey. But, when it was first generation Healey you would use the top holes which did require different lower control arms. Another free 2-cent guess!
DV
PS, Yes..cpteddie's, as long as they are basically the same lenght or able top get the same lenght they should work fine.

[MaSnaka]

Those are not the Hotchkis upper trailing arms on DV's picture that I have seen as p/n 1204AA.

Another note: My trailing arms will be at a significant downward angle if bolted into the lower holes. DV's picture shows them pretty much straight across. Unless the rear end is hanging free and the tires are off the ground.

I did notice Summit offers the same Hotchkis pn 1204AA for about $75 less than the Hotchkis site does if anybody is considering this purchase.

John

[capteddie]

They are Hotchkis uppers. They came for part #1805A. I ordered they whole package not knowing the lowers would not work.

[tcrist]

These are the ones that I bought. They are double adjustable so I do not have to unhook them to adjust. P/N 1204AA, They do come with all of the hardware and grease.




Terry

[capteddie]

Those look a lot nicer than mine. Like I said a couple posts up. I ordered the Mustang upper and lowers as a package. Only to find out that the CRII lowers are shorter, so we used the uppers and made lowers and I still have the Hotchkis lowers on the shelf in the garage

[Double Venom]

Yes,
The car is off the ground and no suport under the wheel. Should have made note of that.
DV

[tcrist]

Ok, I moved the upper trailing arms to the bottom set of holes. Now with my trans and rear diff parallel my driveline angle is pointing down from the trans at about 7 deg. I am thinking that I need to lower the back of the trans about 4 deg and rotate the rear diff up the same. That way the trans and rear diff are parallel and the driveline is pointing down at around 3 deg.
Does this sound correct?
DV, with your experience, about how much should I space the trans mount?
351W, T5 trans, 8.8 rear end.
Your best guess is probably better that most others measurement.
Thanks, Terry

Note: My Cobra is level and I do not want to lower the back any more than it is.

[MaSnaka]

Terry, I don't know the measurements but my understanding is the degrees of pinion from the trans should be about 3 positive (driveshaft pointing down) and the diff should be 3 negative (driveshaft pointing up). So when you hit it, the diff rotates close to 0 degrees pinion thus maximizing effeciency through the drive line. In other words the trans, driveshaft and diff are all in a pretty straight line. Confusing to articulate but I think I have it right.

John

[tcrist]

I think at the least you want the rear diff and the drive line close to parallel when you hit it. As long as it does not rotate past parallel.
That would be my 7 deg, adjust it by 4 deg = 3 deg. I am just looking for confirmation and maybe a referance information about how far to space the trans down.
I guess that I could just crawl under it with a bottle/screw jack, loosen the trans bolts, drop it down that 4 deg and measure it.

Thanks John,

Terry

[Double Venom]

Tery,
OK, let me try to get this simpler...The transmission mount should already be ok (?), not to worry about the angle of the trasmission to much. What ever it is just set the pinion down -from a straight line foward from the center of the pinion-imaginary line- the 2.5 to 3's below this imaginary line. This should get you right in the midle of the ball park.
(Darn, my degree gauge went on the blitz so can't use it for demo shot!
The transmission has already been pre-set by the original engineers.
DV

[tcrist]

Dv, Check out this drawing that I got from a 4X4 web site.


This is the way mine is now except the drive line is at around 7 deg.

Are you saying to leave the motor and trans where they are and just rotate the rear diff to get it within 3 1/2 deg? That would not have the engine/trans and the rear diff parallel.

Terry

[Double Venom]

Terry,
That is a great drawing and explains all-but your dealing with a Cobra and the rear end is NOT going to be level or parallel with the tranny tail shaft to begin with. Your driveshaft is way to short to try and use the above. See how 'A3 and A4' are on the same plane? And the listed rear end is drawn under the assumption (4-wheel drive) it is NOT going to raise/twist under power like a coil/coil-over rear end.

Assuming your rear end is set at close to the above drawing, you STILL want the pinion 'pointing' down a couple of degrees so when the power is supplied it will come back to a maximum of A3 & A4.

There working angle of A5 & A6 is shown the way most cars are set up to be, but again the shortness of the Cobra drive shaft (18 +/- inches) normally doesn't allow this. This is where it is made up with using the control arms to twist the pinion in a negative fashion so when it does go under power and tilts back up, it doesn't go over -0- degrees (which could still give you driveline vibrations even at -0-).

Even IF you were able to duplicate the above drawing you would still want the pinion pointing slightly down to make up for any residual lifting/twisting up under load.

Does this help? Make sense?
DV

[tcrist]

Dv,
So, if I get your explanation correctly. Do not worry about A5-A6 angle. Make sure that A3-A4 is around -3 1/2 deg (rear end pointing down compaired to the transmisssion).

Terry

[Double Venom]

BINGO......Now if you build a streetrod from -0- go back to the diagram!
DV

[tcrist]

Thanks DV.

Terry

[MaSnaka]

Tonight I changed my non-adjustable upper control arms from the top hole to the bottom hole on the chassis. Visually with the upper hole setting the pinion was at an upward angle. The lower hole actually shortens the upper arms by 1/2". Looks better although I don't have a degree finder to check the actual setting. I was surprised at how easy the change was. I raised the car and put the jack stands under the frame just in front of the rear tires, just behind the sidepipe bracket. Used the jack to support the pumpkin until there was no load on the springs. The bolts slipped out and back in no problem. I was expecting a fight. We'll see how she drives tomorrow although I wasn't experiencing any problems before the change.

John

[MaSnaka]

DV,
My trans has a cross member at the tail end of the tranny which is shimmed down from the chassis by 1" spacers. Is this a normal thing to see? I mean should the tranny be shimmed down 1"?

John

[Double Venom]

John,
Seen and done that many times. Must be the tranny. (?) Put a level on the air cleaner and see what you have for angle- should be fairly level.

[Double Venom]

Page 56 of the BIG thread shows how the motor should be...........


Ed's Motor was so 'in line' that I simply grabbed the sidepipes by hand and installed the bolts without having to pry-first time!!

DV